1. Technical Field
The disclosure relates to a lubricating system for an engagement mechanism used in an automatic transmission of a vehicle, for example, and more particularly to a lubricating system for an engagement mechanism having engagement elements that transmit torque by use of frictional force, and a hydraulic part that presses the engagement elements and generates the frictional force.
2. Description of Related Art
A lubricating system that supplies lubricating oil to a frictional engagement element used in an automatic transmission of a vehicle, for example, is known (see, for example, Japanese Patent Application Publication No. 2012-180867 (JP 2012-180867 A)). The lubricating system of the automatic transmission includes a lubrication switching valve that opens and closes a lubricating oil passage, according to an engaging pressure of the frictional engagement element. The frictional engagement element includes a plurality of inner plates, and a plurality of outer plates disposed between adjacent ones of the inner plates. The inner plates and the outer plates provide friction members. The engaging pressure of the frictional engagement element is controlled through supply of the lubricating oil to a hydraulic servo. The friction members contact and engage with each other when the frictional engagement element is in an engaged state in which the engaging pressure is applied to the element, and the friction members are disengaged from each other when the frictional engagement element is in a released state in which the engaging pressure is drained. During transition between the engaged state and the released state, the friction members are in a slipping state, namely, slip relative to each other. When the friction members are in the slipping state, the lubricating oil is supplied so as to prevent seizure of the friction members. In the engaged state and the released state, the lubrication switching valve is closed, and supply of the lubricating oil is stopped.